// Copyright (c) 2012 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef MEDIA_AUDIO_AUDIO_OUTPUT_IPC_H_
#define MEDIA_AUDIO_AUDIO_OUTPUT_IPC_H_

#include <string>

#include "base/memory/shared_memory.h"
#include "base/sync_socket.h"
#include "media/base/audio_parameters.h"
#include "media/base/media_export.h"
#include "media/base/output_device_info.h"
#include "url/origin.h"

namespace media {

// Contains IPC notifications for the state of the server side
// (AudioOutputController) audio state changes and when an AudioOutputController
// has been created.  Implemented by AudioOutputDevice.
class MEDIA_EXPORT AudioOutputIPCDelegate {
public:
    // Called when state of an audio stream has changed.
    virtual void OnError() = 0;

    // Called when an authorization request for an output device has been
    // completed
    virtual void OnDeviceAuthorized(OutputDeviceStatus device_status,
        const media::AudioParameters& output_params,
        const std::string& matched_device_id)
        = 0;

    // Called when an audio stream has been created.
    // The shared memory |handle| points to a memory section that's used to
    // transfer audio buffers from the AudioOutputIPCDelegate back to the
    // AudioRendererHost.  The implementation of OnStreamCreated takes ownership.
    // The |socket_handle| is used by AudioRendererHost to signal requests for
    // audio data to be written into the shared memory. The AudioOutputIPCDelegate
    // must read from this socket and provide audio whenever data (search for
    // "pending_bytes") is received.
    virtual void OnStreamCreated(base::SharedMemoryHandle handle,
        base::SyncSocket::Handle socket_handle,
        int length)
        = 0;

    // Called when the AudioOutputIPC object is going away and/or when the IPC
    // channel has been closed and no more ipc requests can be made.
    // Implementations should delete their owned AudioOutputIPC instance
    // immediately.
    virtual void OnIPCClosed() = 0;

protected:
    virtual ~AudioOutputIPCDelegate();
};

// Provides the IPC functionality for an AudioOutputIPCDelegate (e.g., an
// AudioOutputDevice).  The implementation should asynchronously deliver the
// messages to an AudioOutputController object (or create one in the case of
// CreateStream()), that may live in a separate process.
class MEDIA_EXPORT AudioOutputIPC {
public:
    virtual ~AudioOutputIPC();

    // Sends a request to authorize the use of a specific audio output device
    // in the peer process.
    // If |device_id| is nonempty, the browser selects the device
    // indicated by |device_id|, regardless of the value of |session_id|.
    // If |device_id| is empty and |session_id| is nonzero, the browser selects
    // the output device associated with an opened input device indicated by
    // |session_id|. If no such device is found, the default device will be
    // selected.
    // If |device_id| is empty and |session_id| is zero, the browser selects
    // the default device.
    // Once the authorization process is complete, the implementation will
    // notify |delegate| by calling OnDeviceAuthorized().
    virtual void RequestDeviceAuthorization(
        AudioOutputIPCDelegate* delegate,
        int session_id,
        const std::string& device_id,
        const url::Origin& security_origin)
        = 0;

    // Sends a request to create an AudioOutputController object in the peer
    // process and configures it to use the specified audio |params| including
    // number of synchronized input channels.
    // If no authorization for an output device has been previously requested,
    // the default device will be used.
    // Once the stream has been created, the implementation will notify
    // |delegate| by calling OnStreamCreated().
    virtual void CreateStream(AudioOutputIPCDelegate* delegate,
        const AudioParameters& params)
        = 0;

    // Starts playing the stream.  This should generate a call to
    // AudioOutputController::Play().
    virtual void PlayStream() = 0;

    // Pauses an audio stream.  This should generate a call to
    // AudioOutputController::Pause().
    virtual void PauseStream() = 0;

    // Closes the audio stream which should shut down the corresponding
    // AudioOutputController in the peer process.
    virtual void CloseStream() = 0;

    // Sets the volume of the audio stream.
    virtual void SetVolume(double volume) = 0;
};

} // namespace media

#endif // MEDIA_AUDIO_AUDIO_OUTPUT_IPC_H_
